Telephone dial signals are used to give information and/or instructions to computers. For example, it is known to have calling parties communicate with the bank computer. In greater detail a calling party may want to know the balance in his account at a particular time. He dials the number which causes him to be connected to the bank computer. He then dials an identifying code and a code that will instruct the computer to communicate to him the balance that he has in a particular account. Similiarily, a calling party may telephone signals to instruct a computer of a catalog house or a department store to order material from the catalog according to catalog number.
The dial signals used for such instructions have been double tone, multi-frequency (DTMF) dial signals which provides a generally reliable signal that can be used by telephone circuitry on the receiver side of the phone line circuit. It has been found that rotary dial generated pulses are not reliably detected by telephone circuitry in a "called party" environment.
Systems using DTMF are effective for such applications. However, most of the telephones in the world still use rotary dials and/or electronic pulse systems for signaling rather than the DTMF signals. Therefore, failure of the prior art to provide a reliable system for detecting and counting rotary dial generated pulses for use by computers has inhibited the adaptation of computers systems for telephone transactions by banking and commercial institutions.
Accordingly, it is an object of the present invention to provide techniques and systems to enable pulses (herein after sometimes referred to generically as pulses generated by rotary dials) that are transmitted over telephone lines to be used by computers. The invention thereby enables transactions such as banking transactions to be accomplished with telephones equipped with pulse generators, such as rotary dials. The obstacle to the use of rotary dials for such purpose in the past has been the fact that the rotary dial generated pulses behave as trains of noisy pulses on the receiver side of the called party's line circuit where the computer systems are connected. Thus, pulse operated computer controlled transaction systems in the past have not been able to accurately and reliabily determine the numbers, (information, instructions, etc.) that the calling party customer is sending to the bank or other commercial institutions (the called party).
The most reliable characteristic of the train of rotary dial generated pulses is the time duration of the train. However, even this characteristic is dependent upon the actual dial and the line system between the calling party and the called party. For example every dial generates pulses having slightly different pulse characteristics. Also, there is always cross-talk noises i.e. voice noises on the telephone lines. These noises on the called party side of the line circuit, that is the computer side of the line, can be misinterpreted as pulses and thereby make it impossible for instructions to be sent by the calling party to the computer system. In addition to the other noises the pulse trains generally have what are known as a "tail" at the end of the trains which varies the time length of the pulse train over and above the number of pulses in the train.
Accordingly it is an object of the present invention to overcome these and other difficulties in the use of rotary dials for generating pulses to be used by computer systems for carrying out commercial transactions, for example.